It’s generally good in a competitive game when there’s a lot of interaction. In other words, if your opponent is up to something, it’s good if you can do something about that.

In Codex, your vulnerabilities are on the table and you have to defend them. If you want to cast any spells, you need a hero in play to cast them—and your heroes can be attacked. If you want to make anything beyond the most basic units, you’ll need tech buildings to do that—and your tech buildings can be attacked as well.

In combat, you’re able to attack anything with hit points: any unit, hero, or building. Your ultimate goal is to deal 20 damage to the opponent’s main building—their base—but along the way you’ll probably need to try to take out at least some heroes or tech buildings. Think of this like a “pre-counterspell” in a way. If there’s a certain spell that you really don’t want the opponent to cast, you can kill the hero who casts it, and you’ll have at least one turn of breathing room until they’re able to resummon that hero. If there’s a particular unit you’re afraid of, destroying the tech building that produces it will also give you at least a turn of breathing room until they rebuild that building.

Heroes

Heroes are the stars of your army. You can access them without any randomness: they wait to be summoned in your command zone; you don’t have to draw them from your deck.

Heroes arrive at level 1, and you can spend gold to level them up, even multiple times in a turn. As they level up, they get better stats and new powers (and keep their old powers too). Heroes each have a “spec”. For example, Jaina’s spec is Fire. That means only Jaina can cast “Fire spells.” When heroes reach their max level AND if you didn’t just summon them, they can cast their ultimate spell. Beware of letting your opponent cast ultimate spells—they are really powerful!

Heroes are also great in combat. When a hero levels up from its lowest to middle rank, and when it levels from its middle to last rank, all damage on it is healed. So it can get in an early scuffle and still be fine later.

Killing enemy heroes is so important that you get a bounty for doing so. If you kill an enemy hero on your own turn, all your own heroes (that are in play) level up TWICE for free!

Heroes are fun and flavorful and give the game a ton of character. From a game mechanics perspective, they’re really important because they force you to have your vulnerabilities (in this case, your ability to cast certain spells) on the table where the opponent can interact with them.

Tech Buildings

You start the game with some weak units in your deck that you can summon from your base. If you want more powerful units though, you’ll need to build your tech I building. If you have a tech I building, you can then build your tech II building. That then lets you build your tech III building, which can then produce absurdly powerful, game-winning units.

You have access to three different specs during a game of Codex. For example, an all-red deck would have access to the Anarchy, Blood, and Fire specs. Your tech I building lets you build units from any of those specs. In other words, a tech I building lets you play any card with a bronze bottom on it, regardless of the spec.

At the tech II level, you have to specialize and choose a particular spec though. You’ll only be able to make tech II units of that spec and you’ll be locked into that same spec when you build your tech III building. In practice, this allows for tighter counter-play. If you have no idea what the opponent might even build, it’s hard to develop counter-measures. If you at least know the spec they chose this particular game, you have some basis to choose how to respond.

What if you want to to use two different specs in a game though? You actually CAN do that. Your base can hold exactly one add-on building. There are a few to choose from, and one of them—the Tech Lab—allows you to access two specs at once. That can be powerful, but the other add-ons are useful too!

There are lots of tricky build orders you can use, but the most standard approach is to lean on one particular hero (for spells) and one particular spec at the tech II level (for units). These do NOT have to match. For example, you might rely on the Blood hero and his Blood spells, but you are free to have your tech II building specialize in Fire if you want. That means you have 9 different routes (3 choices of heroes x 3 choices of tech specializations) in standard builds. That doesn’t even include the many more build orders you can explore with strategies that rely entirely on spells, or that combine two tech II specs using the Tech Lab.

Pacing

You have to pace yourself when you build your tech buildings. Each one takes one turn to finish constructing and you can’t even start building them until you have the requisite number of workers. That means if you build them “on schedule” as soon as you’re usually allowed to, you’ll get your tech I building in place on turn 3, your tech II on turn 5, and your tech III on turn 7. But things don’t always go as planned!

Pressure your opponent and make them spend so much on defense that they can’t afford to build tech buildings. Or destroy a tech building if you can and slow down their progression. You can’t just play solitaire here; Codex is highly interactive so your ability to expand your tech or to deny your opponent’s tech is tightly linked to how much you’re able to pressure each other in combat.

Heroes and tech buildings add a lot of flavorful fun to Codex because they match RTS games such as Warcraft 3, but they don’t exist in the game because of that flavor. Quite the opposite: I chose the RTS theme specifically because the game dynamics are so good when you have to protect your ability to cast spells (from heroes) and your ability to make certain kinds of units (from tech buildings). RTS video games are a great match and there’s a lot of parallels for Starcraft and Warcraft 3 fans to enjoy.